SWB’s the original aluminum Double-Loc Servo Arm User holes threaded for 4/40 These arms are not only designed to clamp around the output shaft, but they also make up for any inconsistencies in the output shaft sizes. Half arms are measured from the servo screw hole to the outside hole.

Full arms are measured from the servo screw hole to the outside hole, 2X Example” 1-1/4 Full arms are 2-1/2” from outside hole to outside hole.